This project will be concerned primarily with the analysis of the way that visual interneurones encode movement and directionality. The approach will be comparative. Intracellular recordings will be made from cells in the medullae of flies and in ganglion cells and other cells of the turtle retina in an effort to follow the flow of information about movement from receptors to directionally-selective or movement-sensitive cells. Intracellular stainings will be used to help define the "wiring diagrams" of the movement-detecting networks. Experiments will attempt to provide cross-fertilization of stimulus approaches used to analyze directionality in vertebrate retinal ganglion cells on the one hand, and those developed for nonlinear analyses of turning behavior ininsects, on the other hand.